In a typical thin film read/write transducer, active transducer components (a reader and a writer) are covered by a thick alumina overcoat layer. The alumina overcoat layer mechanically protects the transducer and allows mechanical assembly with suspension components and electrical leads without damage to the transducer. Metallic studs, typically formed of copper, pass through the thick overcoat layer and complete electrical connections between the transducer components and external bond pads that contact the electrical leads.
The studs are formed first, and then the thick alumina overcoat layer is deposited around the studs. One known problem with the alumina overcoat masking process is a defect called “trenching.” When studs are placed close to one another, during the subsequent alumina deposition process, the mask tends to shield a space between the studs, resulting in a trench in the alumina layer in the space between the studs. The trench is a void in the overcoat layer that is not filled with alumina. When there is significant trenching, the trench tends to fill with debris during subsequent processing steps such as a chemical mechanical polishing (CMP) process. If trenching occurs, adjacent studs can be electrically shorted to one another and the read/write transducer becomes useless.
The temperature of the read/write transducer changes significantly during disk or tape drive operation. The studs are typically made of copper and have a larger coefficient of temperature expansion (TCE) that the thick alumina layer. As the read/write transducer heats up, the TCE mismatch of the studs can deform the head as well as the slider upon which the read/write head is deposited. This deformation includes both increased pole tip protrusion (Thermal-PTR) and slider bending (Cross-curve change). There is a desire to reduce the diameter of the studs in order to reduce bending and deformation.
As recording densities increase, read/write heads are being improved to integrate additional features such as fly height sensors and mechanical microactuators in the read/write head itself. There is a desire to provide read/write heads that have more studs for connections to these additional features while at the same time reducing the size of the read/write head so that there is less space available for the studs. As attempts are made to produce read/write transducers with smaller diameter, more closely spaced studs, problems with trenching and deformation due to thermal mismatch increase.
In existing read/write transducers, sliders are large and at the same time, the number of required electrical connections is low. This allows placing studs far enough from each other and from the read/write transducer to reduce thermo-mechanical interaction. Recent heads for high areal density are smaller and at the same time, the number of required electrical connections is increasing.
A method and apparatus for providing smaller diameter, more closely spaced studs on smaller read/write heads without high failure rates due to trenching and excessive distortion and bending. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.